French Pat. No. 1,475,665 discloses a RFI suppressor cable, resisting and absorbing, making application of the absorptive principle (see French Pat. Nos. 1,205,158--74,223 and 80,097 and U.S. patent application Ser. No. 855,593 of Nov. 29, 1977 now abandoned) of the medium surrounding the conductor which conductor can be straight or helicoidal, but not metallic, formed by a base of plastic material in which the desired conductivity is obtained by a conductive charge of carbon and/or metallic powder. In this way resistance values of 500 to 3000 .OMEGA. per meter may be obtained, the action of which is to be added to the absorptive effect of the surrounding medium, in view of suppressing the conduction and radiation of RFI in the internal combustion engine ignition circuits.
This type of realization presents some drawbacks, such as the impossibility of obtaining stable values of conductor resistance (more especially with temperature) and a mechanical quality good enough for ensuring a sufficient life expectancy, due to the multiple strains of various kinds such as mechanical, thermal, etc. Moreover, these problems are presently enhanced by the evolution and development of modern techniques for engine ignition, the systematic use of radio equipment (reception and transmission onboard and the ever increasing use of electronic equipment onboard, all of which is requiring higher values of resistance. For example, 1000 to 100,000 .OMEGA./m for linear conductors are usual nowadays; 5000 .OMEGA./m are currently used in France and 15,000 .OMEGA./m are currently used in the United States.
Then, if a metallic conductor is convenient for the realization of the smaller values, the higher values show a contradictory evolution: the realization of the above cited high values of resistance with a favourable helicoidal structure (allowing the use of a great length of conductor) reaches the mechanical limit for the practical realization or even goes beyond this limit. For example, the realization of a cable of 5000 .OMEGA./m in the form of an helix of 3 mm diameter, with thirty turns per cm, with the strongest metallic alloys presently known, requires the use of a wire with a diameter comprised between 6 and 8 hundredths of a mm, which is inconsistent with the strength and reliability on the long term, in the considered use. Beside this application to ignition cables, there is evidently a number of other wires and cables for which such a structure is of advantage for the realization of a transmission absorbing interference voltages or fields.